Method of reclaiming worn piston pins



July 30, 1929. E. J. OPIE ET AL METHOD OF RECLAIMING WORN PISTON PINSFiled 001;. 19, 1927 m 2% a M ATTORNEYS Patented July 30, 1929.

ENT-Mme Enn'ris'r than orrn for masses, m iroiin s. iqa n' wbamrgjoaanaemi NEW; Yonn jassrenofnsjo r. natwraornnmdooMPAnY; or ALBANY, newYonx'; A CORPORATION or DELAWARE? ivrET'Hon es nnominvr ms worm "PISTONPINS;

Applicatin' filed octoterfi'e, 1927". Serial No. 227,193

This'invention relates tothe reclamation of worn piston pins whereby thenormal externalidimensions of such P1I1S are restored so that the pinsmay be used again in place of new pins.

Thousands of worn piston pins are removed annually from internalcombustion en gines. The'wear upon these pins occurs at the outerperiphery thereof and consequen tly the pins cannot be restoredbysim'ply machining the outer surface. The worn'piston pins have,therefore, no commercial value and they are scrapped; Since such pinsare made of high'grade steel and are relatively expen-' siveconsiderable loss results from the scrappingrof the pins.

It is the'objectof'the present invention to provide asimpleandeconomicalmethod for the'reclaiming of pistoir'pins by restoring them tosubstantially their original condition and dimensions. p A g a We havediscovered that worn pistonpins can be reclaimed by. subjecting them toex pansionso as to force the metal outwardly and'enlarging thedimensions sufficiently to permit the machining of the pins to theiroriginal and normal dimensions. Piston pins are hollow cylinders ofhardened steel. The desired expansion can be accomplished readily'byannealing the pins so as to make the metal malleable and by then forcinga tool of suitable form through the hollow pinsso that'the metal isforced outwardly and the externa'l'dimensio'ns are increased according-1y. 'In'carrying out the invention the an nealed pin may be placed in asuitable machine adapted to apply pressure to the expanding'tooh'forexample; inan hydraulic press, the external surface of the pin beingunconstrained so as to permit the desired expansion. A.tool, forexample, a hardened steel balLhaVinga diameter slightly larger.

than the/hole in the pin can then be, forced through the hole bypressure applied to the ballwhile the pin is cold; One. or more ballsinay be'used in succession if desired; the balls being of increasingdiameter to accomplish the desiredrarnountef expat When the has'heen dto the ale sired extent it is removed from the press, and again hardenedby heating and quenchingin the ordinary manner. The pin may then beground to the desired size and"l apped to a finish. It is then insubstantially its original condition and form and is adapted for reuseexactly as anew pin would be used. We have found-that the annealing andrehardening of the pin combined with the effect of pressure exerted bythe hydraulic or other press has a tendency to refine the texture of thesteel so that the quality ofthe reclai'medipin is actual ly' equal to orbetter than'that' of a new pin produced from similar metal. I

rVVh ile we preferto employa ball'orballs as an expansion tool,otherfdevices ofa similar nature can be used. Thus; a t'ool having arounded or conical end of larger diameter than thehole in the pin can beforced through the hole by a press. Or suitable, split collars may beinserted in the pin and the collar and pin may be expanded then bydriving a conical toolinto the collar. In place of a singleconical toolintroduced at one end of the pin two tools maybe insertedfrom op positeends and forced together by the application of pressure in any suitableway. The pressure may be exertedbya press such as an hydraulic press ora threaded 'inember can be inserted throughthe toolswhich maybe thenSimilarly; the w ger ped to s ,may be threaded in opposite dire ti dmay-be connected by a threadedjmember so that when the latter isturnedthe tools are drawn together, for'the purpose of expanding thepin; These and other equiyalent means may be utilized to accomplish theprimary purpose of the invention which is the expansion of'the pin toincrease the external dimensions thereof so asto permit ieiiia'ehinin'gthereof to the dimensions'necessary fora finished pin.

; t The invention will be more fully described with reference totheacc'ompanying drawing in which the preferred. forms of apparatusadapted forthe practice ofthe invent-ion are illus ratedbeing pnderstood that such din t sgintended merel ti; ind cate invention perature.

which is not limited to the use of any specific apparatus. In thedrawing,

Fig. 1 indicates an hydraulic press with a piston pin supported thereinin position to receive the tool which is forced therethrough;

Fig. 2 is a sectional view of a pin illustrating the expansion resultingfrom the move ment of the tool through the pin;

Fig. 3 is a sectional view of the pin at the completion of the expandingoperation;

Figs. 4, 5, 6 and 7 are fragmentary views illustrating different formsof tools Which may be utilized for the purpose of the invention; and

Figs. 8 to 12 inclusive are sectional views illustrating other forms oftools adapted for similar use.

As hereinbefore indicated, the worn piston pin which is made of hardenedsteel is first annealed by heating it to the necessary temperature fromwhich temperature it is permitted to cool to normal atmospheric tem- Theannealed pin is then mount-,

7 ed in a press comprising a frame or support 6 and a plunger 7, thelatter being operated by hydraulic pressure in the usual manner, thepressure available being sufiicient to force the tool 8 through the pin.The tool may be a hardened steel ball as indicated in the drawing and itmay be engaged by the end of-the plunger 7 to permit the application offorce. The pin 5 is unconstrained and upon the downward movement of theplunger the ball is carried through the hole therein, causingthe metalto flow outwardly, thus enlarging the external dimensions of the pin."The size of the tool employed should be such as to increase the externaldimensions to the required degree or another ball of larger dimensionsmay be forced subsequently through the hole to further expand the metal.

The expanded pin is removed from the press. It is again hardened byheating and quenching in accordance with the usual practice in producinghardened steel articles such as piston pins, and it is then ground topredetermined size and lapped to a finish.

Referring to Fig. 4 of the drawing we may employ in place of, a ball atool having a shank 9 and an enlarged end 10 which is generallyspherical in form. This tool may be forced through the pin by theapplication of pressure exactly as the ball is used in the precedingembodiment of the invention. Similarly as in Fig. 5 the tool maycomprise a shank 11 with a conical end 12, the larger dimension of whichis suflicient to afford the desired degree of expansion when it isforced through the pin. In Fig. 6 of the drawing the tool comprises ashank 13 with a conical end 14 thereon, the cone being, however,reversed, andin Fig. 7 the shank 15 is provided with a semi-sphericalend 16. 'The several forms of tools may be used in place of the ball andwhen actuated by pressure in the manner hereinbefore indicated willserve to expand the pin and thus increase its external dimension.

In Fig. 8 a split collar 17 is disposed within a pin 18 and a conicaltool 19 is forced therethrough to expand the collar and consequently thepiston pin to the desired dimensions. The tool may be actuated byhydraulic pressure or otherwise. Similarly in Fig. 9 a split collar 20is disposed within the pin 21 and conical tools 22 are forced fromopposite ends ofthe pin into the collar for the purpose of expanding thepin. In Fig. 10 the tools 23 which are conical in form and hollow areconnected by a bolt 24 having a nut 25 threaded on the end thereof. Byturning the nut the tools may be drawn together for the purpose ofexpanding the pin 26.

In Fig. 11 a split collar 27 is disposed within the pin 28 and ahardened ball 29 is forced through the collar by hydraulic or otherforce supplied thereto to expand the pin as in the preceding embodimentsof the invention. In Fig. 12 the conical tools 30 are internallythreaded and are connected by a threaded member 31, the threads beingreversed so that when the threaded member is turned the tools are drawntogether to expand the pin 32.

The invention does not depend upon the use of tools of any particularform or upon the application of force provided in any special manner.The purpose of the invention is to increase the external diameter of theworn piston pin by forcing the metal outwardly, thus permittingre-machining of the pin to predetermined dimensions. The expansion ofthe metal in the manner described improves the quality thereof andconsequent ly the hardness and durability of the pin when the latter hasbeen rehardened and finished. Pins thus reclaimed are, therefore, notonly suitable for further use but are actually superior to pinsmanufactured from similar metal.

As hereinbefore indicated, various changes may be made in the details ofthe operation and in the apparatus employed without departing from theinvention or sacrificing any of its advantages. 1

We claim 1. The method of reclaiming worn piston pins, which comprisesannealing the pin, forcing the metal outwardly from the interior thereofto increase the external dimension beyond the normal finished dimensionof the pin, rehardening and finishing the pin to the normal dimension.

2. The method of reclaiming worn piston pins, which comprises annealingthe pin, subjecting it to internal pressure while the external surfaceis unconstrained to force the metal outwardly and to increase theexternal dimension beyond the normal dimension of sion beyond the normalfinished dimension the pin, rehardening and finishing the pin to of thepin, rehardening and finishing the pin the normal dimension. to thenormal dimension. 1

3. The method of reclaiming Worn piston In testimony whereof We affixour signa- 5 pins, Which comprises annealing the pin, forctures.

ing the cold metal outwardly from the in- ERNEST JOHN OPIE. teriorthereof to increase the external dimen- JOHN S. GOLDSWORTHY.

